Bash Bash Arithmetic Arithmetic command
Example
let
let num=1+2
let num="1+2"
let 'num= 1 + 2'
let num=1 num+=2
You need quotes if there are spaces or globbing characters. So those will get error:
let num = 1 + 2 #wrong
let 'num = 1 + 2' #right
let a[1] = 1 + 1 #wrong
let 'a[1] = 1 + 1' #right
(( ))
((a=$a+1)) #add 1 to a
((a = a + 1)) #like above
((a += 1)) #like above
We can use (()) in if. Some Example:
if (( a > 1 )); then echo "a is greater than 1"; fi
The output of (()) can be assigned to a variable:
result=$((a + 1))
Or used directly in output:
echo "The result of a + 1 is $((a + 1))"
